The invention relates to an arrangement for a vibration damper of a vehicle, having at least one damping cylinder made from a fiber composite material, a guiding element which is arrangeable in a guiding end region of the damping cylinder, which guiding end region is arranged at one end of the damping cylinder, for guiding a piston rod of a piston arrangeable movably in the damping cylinder, and a fastening element which is arrangeable in a fastening end region of the damping cylinder, which fastening end region is arranged at the other end of the damping cylinder, for fastening the damping cylinder to a further component of the vehicle.
Furthermore, the invention relates to a vibration damper for a vehicle.
Components of vibration dampers are conventionally at least partially formed from a metallic material, such as, for example, steel or aluminum, from plastic or from a fiber composite material. In particular, it is known to produce a damping cylinder, also referred to below as supporting tube, of a vibration damper from a fiber composite material in order to reduce the weight of the supporting tube or of a correspondingly equipped vibration damper. It is also known to produce further components of a vibration damper, such as, for example, a spring plate, from a fiber composite material in order to save weight.
A guiding element is customarily arranged at one end of the supporting tube to linearly guide a piston rod within the supporting tube. On the end of the piston rod is a vibration-damping piston which is guided movably in the supporting tube. A fastening element for fastening the supporting tube to a further component of a vehicle is customarily arranged at the other end of the supporting tube.
The supporting tube can be connected to the guiding element and the fastening element in an integrally bonded manner via an adhesive connection. Such an integrally bonded connection of the supporting tube to the guiding element and to the fastening element is disadvantageously associated with a risk of the formation of gas leakages in the region of the adhesive connections. In addition, a corresponding adhesive connection conceals the risk of a premature and abrupt total failure of the adhesive joint and requires clean surfaces with precise tolerances and which generate additional premachining and/or finishing work in the manufacturing of vibration dampers. Furthermore, during the curing of the adhesive connection, the adhesive customarily shrinks, which may likewise bring about leakages and lead to a poor state of connection.
Alternatively, the supporting tube can be connected to the guiding element and to the fastening element in a form-fitting manner, for example by winding or braiding a “T-porcupine roller” with a fiber composite material, in particular by integrating this connecting technique into the manufacturing process of vibration dampers. A form-fitting T-porcupine-roller connection results in additional component costs for the T-porcupine roller. In addition, the integration of this connecting technique into the manufacturing process of a correspondingly designed vibration damper turns out to be costly and additionally conceals the risk of the connection becoming detached because of different coefficients of thermal expansion of the interconnected components, in particular because of the temperatures prevailing during curing of the fiber composite material.
The connecting techniques mentioned therefore require a complicated manufacturing and preparation of the joining points on the supporting tube and on the guiding element and the fastening element, as a result of which a desired lightweight construction of vibration dampers is restricted.
It is the object of the invention to provide a novel possibility for forming high-quality, lightweight vibration dampers which can be produced cost-effectively.
According to the invention, at least one of the two end regions of the damping cylinder is of conical or wedge-shaped design, and an element arranged in each of the at least one end region has a corresponding conical or wedge shape. At the guiding end region the conical or wedge-shaped design tapers toward that end face of the guiding end region, and at the fastening end region the conical or wedge-shaped design widens toward the end face of the fastening end region.
By means of the conical or wedge-shaped configuration of the at least one end region of the damping cylinder and the corresponding external shape of the element to be connected to said end region, a clamping fit can be produced by means of a frictional connection, which brings about a highly sturdy connection between the supporting tube and the element. By means of forces acting on the connection between the damping cylinder and the element when a the damping cylinder is assembled into a vibration damper, the quality of the connection is increased further by the conical or wedge-shaped configuration of the end region of the damping cylinder and of the external shape of the element.
The shaping of the end region or the external shape of the element can be conical or wedge-shaped. In contrast to a conical configuration, a wedge-shaped configuration has in particular a polygonal area instead of a circular area.
According to an advantageous refinement, the arrangement has at least one clamping sleeve which is arrangeable on the end region in a manner at least partially surrounding the end region and has at least one internal shape of corresponding conical or wedge-shaped design. By arrangement of the clamping sleeve on the end region in a manner at least partially surrounding the end region, the end region is supported from the outside, and therefore the damping cylinder or the end region thereof can be connected to the element by application of relatively large clamping forces, which is equivalent to an increase in the quality of the connection between the end region and the element.
According to a further advantageous refinement, the clamping sleeve is at least partially formed from a metal or a fiber composite material. Aluminum or steel are particularly suitable as the metal. The fiber composite material can be in the form of fiber composite plastic. In a further advantageous embodiment, the fibers of the fiber composite material are arranged running in the circumferential direction of the clamping sleeve to absorb relatively large clamping forces which are produced by the connection between the end region of the damping cylinder and the element. The greater the applied clamping forces the better the quality of the connection and the resistance against leakage.
Furthermore, it is considered advantageous if the fiber composite material contains a thermoplastic or thermosetting plastic.
According to a further advantageous refinement, the clamping sleeve is at least partially adhesively bonded to the end region. This reinforces the connection produced between the end region of the damping cylinder and the element.
In a further advantageous refinement, the clamping sleeve and the end region of the damping cylinder are at least partially connected to each other by a combined, isochronous pressing process with friction welding. This is of advantage in particular if both the clamping sleeve and the damping cylinder are formed with a thermoplastic fiber composite material. The friction welding constitutes a simple and rapid joining method here.
In an advantageous manner, the clamping sleeve which is arrangeable on the guiding end region of conical or wedge-shaped design forms a stop cap. When a vibration damper is completely retracted, the stop cap assists in ensuring that forces introduced into the clamping sleeve by physical contact between the clamping sleeve and a further component of the vibration damper or a further component of a vehicle are introduced into the fiber composite material as compressive forces.
According to a further advantageous refinement, the clamping sleeve which is arrangeable on the guiding end region has an encircling collar forming a spring plate, thereby combining two components of a vibration damper to form a single component which takes on the functions of the two original components.
Furthermore, it is considered advantageous if at least one projection arranged in an at least partially encircling manner is arranged on the inner side of the clamping sleeve in a previous manufacturing process step or retrospectively by a pressing or rolling operation, wherein grooves formed in a substantially complementary manner with respect to the projection are arranged on the outer side of the end region. This produces an additional form-fitting connection between the clamping sleeve and the end region. In the case of a clamping sleeve and an end region made from a thermoplastic fiber composite material, the projection and the groove can be formed in one working step using a hot pressing method, while the clamping sleeve is fixed to the end region.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.